The present invention relates to variable magnification optics for use in an electrophotographic copier, facsimile machine, laser printer or similar image forming apparatus and, more particularly, to variable magnification optics constructed to promote accurate and smooth movement of various optical members thereof in the event of a change of magnification.
Many modern electrophotographic copiers, for example, are provided with a magnification changing mechanism for enlarging or reducing a document image to be reproduced. The magnification changing mechanism includes various optical members such as a lens and mirrors which are movable to set up a desired magnification. The optical members have to be moved over a substantial distance in the event of, among others, reduction, so that the optics occupies much of a limited space available in the copier. This translates into an increase in the overall dimensions of the copier and thereby degrades the manipulability. While the optical members have to be moved accurately and smoothly in the event of magnification change which may be either enlargement or reduction, variable magnification optics capable of sufficiently meeting such a need have not yet been reported.